Syntactic Control of Interference Revisited

In Syntactic Control of Interference (POPL, 1978), J. C. Reynolds proposes three design principles intended to constrain the scope of imperative state effects in Algol-like languages. The resulting linguistic framework seems to be a very satisfactory way of combining functional and imperative concepts, having the desirable attributes of both purely functional languages (such as pcf) and simple imperative languages (such as the language of while programs). However, Reynolds points out that the obvious syntax for interference control has the unfortunate property that fi-reductions do not always preserve typings. Reynolds has subsequently presented a solution to this problem (ICALP, 1989), but it is fairly complicated and requires intersection types in the type system. Here, we present a much simpler solution which does not require intersection types. We first describe a new type system inspired in part by linear logic and verify that reductions preserve typings. We then define a class of bireflective models, which provide a categorical analysis of structure underlying the new typing rules; a companion paper Bireflectivity, in this volume, exposes wider ramifications of this structure. Finally, we describe a concrete model for an illustrative programming language based on the new type system; this improves on earlier such efforts in that states are not assumed to be structured using locations

Collaboration With Deaf Communities to Conduct Accessible Health Surveillance

Introduction Populations of deaf sign language users experience health disparities unmeasured by current public health surveillance. Population-specific health data are necessary to collaboratively identify health priorities and evaluate interventions. Standardized, reproducible, and language-concordant data collection in sign language is impossible via written or telephone surveys. Methods Deaf and hearing researchers, community members, and other stakeholders developed a broad computer-based health survey based on the telephone-administered Behavioral Risk Factor Surveillance System. They translated survey items from English to sign language, evaluated the translations, and filmed the survey items for inclusion in their custom software. They initiated the second Rochester Deaf Health Survey in 2013 (n=211). Analyses (conducted in 2015) compared Rochester Deaf Health Survey 2013 findings with those of the Behavioral Risk Factor Surveillance System with the general adult population in the same community (2012, n=1,816). Results The Rochester Deaf Health Survey 2013 participants’ mean age was 44.7 (range, 18—87) years. Most were deaf since birth or early childhood (87.1%) and highly educated (53.6% with ≥4 years of college). The median household income was \u3c $35,000. The prevalence of current smokers was low (8.1%). Nearly all (93.8%) reported having health insurance, yet barriers to appropriate health care were evident, with high emergency department use (16.2% with two or more past-year visits) and 22.7% forgoing needed health care in the past year because of cost. Conclusions Community-engaged research with deaf populations identifies strengths and priorities, providing essential information otherwise missing from existing public health surveillance, and forming a foundation for collaborative dissemination to facilitate broader inclusion of deaf communities

Deep Impact: Observation From A Worldwide Earth-Based Campaign

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet\u27s behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics

The Deep Impact Earth-Based Campaign

Prior to the selection of the comet 9P/Tempel 1 as the Deep Impact mission target, the comet was not well observed. From 1999 through the present there has been an intensive world-wide observing campaign designed to obtain mission critical information about the target nucleus, including the nucleus size, albedo, rotation rate, rotation state, phase function, and the development of the dust and gas coma. The specific observing schemes used to obtain this information and the resources needed are presented here. The Deep Impact mission is unique in that part of the mission observations will rely on an Earth-based (ground and orbital) suite of complementary observations of the comet just prior to impact and in the weeks following. While the impact should result in new cometary activity, the actual physical outcome is uncertain, and the Earth-based observations must allow for a wide range of post-impact phenomena. A world-wide coordinated effort for these observations is described. © 2005 Springer

The Deep Impact Earth-Based Campaign

Prior to the selection of the comet 9P/Tempel 1 as the Deep Impact mission target, the comet was not well observed. From 1999 through the present there has been an intensive world-wide observing campaign designed to obtain mission critical information about the target nucleus, including the nucleus size, albedo, rotation rate, rotation state, phase function, and the development of the dust and gas coma. The specific observing schemes used to obtain this information and the resources needed are presented here. The Deep Impact mission is unique in that part of the mission observations will rely on an Earth-based (ground and orbital) suite of complementary observations of the comet just prior to impact and in the weeks following. While the impact should result in new cometary activity, the actual physical outcome is uncertain, and the Earth-based observations must allow for a wide range of post-impact phenomena. A world-wide coordinated effort for these observations is described. © Springer 2005

Spitzer Spectral Observations Of The Deep Impact Ejecta

Spitzer Space Telescope imaging spectrometer observations of comet 9P/Tempel 1 during the Deep Impact encounter returned detailed, highly structured, 5- to 35-micrometer spectra of the ejecta. Emission signatures due to amorphous and crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas and ice, and sulfides were found. Good agreement is seen between the ejecta spectra and the material emitted from comet C/1995 01 (Hale-Bopp) and the circumstellar material around the young stellar object HD100546. The atomic abundance of the observed material is consistent with solar and C1 chondritic abundances, and the dust-to-gas ratio was determined to be greater than or equal to 1.3. The presence of the observed mix of materials requires efficient methods of annealing amorphous silicates and mixing of high- and low-temperature phases over large distances in the early protosolar nebula

Spitzer Space Telescope Observations Of The Nucleus Of Comet 103P/Hartley 2

We have used the Spitzer Space Telescope InfraRed Spectrograph (1RS) 22-μm peakup array to observe thermal emission from the nucleus and trail of comet 103P/Hartley 2, the target of NASA\u27s Deep Impact Extended Investigation (DIXI). The comet was observed on UT 2008 August 12 and 13, while 5.5 AU from the Sun. We obtained two 200 frame sets of photometric imaging over a 2.7 hr period. To within the errors of the measurement, we find no detection of any temporal variation between the two images. The comet showed extended emission beyond a point source in the form of a faint trail directed along the comet\u27s antivelocity vector. After modeling and removing the trail emission, a NEATM model for the nuclear emission with beaming parameter of 0.95 ± 0.20 indicates a small effective radius for the nucleus of 0.57 ± 0.08 km and low geometric albedo 0.028 ± 0.009 (1δ). With this nucleus size and a water production rate of 3 × 10 28 molecules s -1 at perihelion, we estimate that ∼100% of the surface area is actively emitting volatile material at perihelion. Reports of emission activity out to ∼5 AU support our finding of a highly active nuclear surface. Compared to Deep Impact\u27s first target, comet 9P/Tempel 1, Hartley 2\u27s nucleus is one-fifth as wide (and about one-hundredth the mass) while producing a similar amount of outgassing at perihelion with about 13 times the active surface fraction. Unlike Tempel 1, comet Hartley 2 should be highly susceptible to jet driven spin-up torques, and so could be rotating at a much higher frequency. Since the amplitude of nongravitational forces are surprisingly similar for both comets, close to the ensemble average for ecliptic comets, we conclude that comet Hartley 2 must have a much more isotropic pattern of time-averaged outgassing from its nuclear surface. Barring a catastrophic breakup or major fragmentation event, the comet should be able to survive up to another 100 apparitions (∼700 yr) at its current rate of mass loss. © 2009. The Astronomical Society of the Pacific. AU rights reserved